#! /usr/bin/python3
#
# trace Trace a function and print a trace message based on its
# parameters, with an optional filter.
#
# usage: trace [-h] [-p PID] [-L TID] [-v] [-Z STRING_SIZE] [-S] [-c cgroup_path]
# [-M MAX_EVENTS] [-s SYMBOLFILES] [-T] [-t] [-K] [-U] [-a] [-I header]
# [-A]
# probe [probe ...]
#
# Licensed under the Apache License, Version 2.0 (the "License")
# Copyright (C) 2016 Sasha Goldshtein.
from __future__ import print_function
from bcc import BPF, USDT, StrcmpRewrite
from functools import partial
from time import strftime
import time
import argparse
import re
import ctypes as ct
import os
import traceback
import sys
class Probe(object):
probe_count = 0
streq_index = 0
max_events = None
event_count = 0
first_ts = 0
first_ts_real = None
print_time = False
print_unix_timestamp = False
use_localtime = True
time_field = False
print_cpu = False
print_address = False
tgid = -1
pid = -1
uid = -1
page_cnt = None
build_id_enabled = False
aggregate = False
symcount = {}
done = False
@classmethod
def configure(cls, args):
cls.max_events = args.max_events
cls.print_time = args.timestamp or args.time
cls.print_unix_timestamp = args.unix_timestamp
cls.use_localtime = not args.timestamp
cls.time_field = cls.print_time and (not cls.use_localtime)
cls.print_cpu = args.print_cpu
cls.print_address = args.address
cls.first_ts = BPF.monotonic_time()
cls.first_ts_real = time.time()
cls.tgid = args.tgid or -1
cls.pid = args.pid or -1
cls.uid = args.uid or -1
cls.page_cnt = args.buffer_pages
cls.bin_cmp = args.bin_cmp
cls.build_id_enabled = args.sym_file_list is not None
cls.aggregate = args.aggregate
if cls.aggregate and cls.max_events is None:
raise ValueError("-M/--max-events should be specified"
" with -A/--aggregate")
def __init__(self, probe, string_size, kernel_stack, user_stack,
cgroup_map_name, name, msg_filter):
self.usdt = None
self.streq_functions = ""
self.raw_probe = probe
self.string_size = string_size
self.kernel_stack = kernel_stack
self.user_stack = user_stack
self.probe_user_list = set()
Probe.probe_count += 1
self._parse_probe()
self.probe_num = Probe.probe_count
self.probe_name = "probe_%s_%d" % \
(self._display_function(), self.probe_num)
self.probe_name = re.sub(r'[^A-Za-z0-9_]', '_',
self.probe_name)
self.cgroup_map_name = cgroup_map_name
if name is None:
# An empty bytestring is always contained in the command
# name so this will always succeed.
self.name = b''
else:
self.name = name.encode('ascii')
self.msg_filter = msg_filter
# compiler can generate proper codes for function
# signatures with "syscall__" prefix
if self.is_syscall_kprobe:
self.probe_name = "syscall__" + self.probe_name[6:]
def __str__(self):
return "%s:%s:%s FLT=%s ACT=%s/%s" % (self.probe_type,
self.library, self._display_function(), self.filter,
self.types, self.values)
def is_default_action(self):
return self.python_format == ""
def _bail(self, error):
raise ValueError("error in probe '%s': %s" %
(self.raw_probe, error))
def _parse_probe(self):
text = self.raw_probe
# There might be a function signature preceding the actual
# filter/print part, or not. Find the probe specifier first --
# it ends with either a space or an open paren ( for the
# function signature part.
# opt. signature
# probespec | rest
# --------- ---------- --
(spec, sig, rest) = re.match(r'([^ \t\(]+)(\([^\(]*\))?(.*)',
text).groups()
self._parse_spec(spec)
# Remove the parens
self.signature = sig[1:-1] if sig else None
if self.signature and self.probe_type in ['u', 't']:
self._bail("USDT and tracepoint probes can't have " +
"a function signature; use arg1, arg2, " +
"... instead")
text = rest.lstrip()
# If we now have a (, wait for the balanced closing ) and that
# will be the predicate
self.filter = None
if len(text) > 0 and text[0] == "(":
balance = 1
for i in range(1, len(text)):
if text[i] == "(":
balance += 1
if text[i] == ")":
balance -= 1
if balance == 0:
self._parse_filter(text[:i + 1])
text = text[i + 1:]
break
if self.filter is None:
self._bail("unmatched end of predicate")
if self.filter is None:
self.filter = "1"
# The remainder of the text is the printf action
self._parse_action(text.lstrip())
def _parse_offset(self, func_and_offset):
func, offset_str = func_and_offset.split("+")
try:
if "x" in offset_str or "X" in offset_str:
offset = int(offset_str, 16)
else:
offset = int(offset_str)
except ValueError:
self._bail("invalid offset format " +
" '%s', must be decimal or hexadecimal" % offset_str)
return func, offset
def _parse_spec(self, spec):
parts = spec.split(":")
# Two special cases: 'func' means 'p::func', 'lib:func' means
# 'p:lib:func'. Other combinations need to provide an empty
# value between delimiters, e.g. 'r::func' for a kretprobe on
# the function func.
if len(parts) == 1:
parts = ["p", "", parts[0]]
elif len(parts) == 2:
parts = ["p", parts[0], parts[1]]
if len(parts[0]) == 0:
self.probe_type = "p"
elif parts[0] in ["p", "r", "t", "u"]:
self.probe_type = parts[0]
else:
self._bail("probe type must be '', 'p', 't', 'r', " +
"or 'u', but got '%s'" % parts[0])
self.offset = 0
if "+" in parts[-1]:
parts[-1], self.offset = self._parse_offset(parts[-1])
if self.probe_type == "t":
self.tp_category = parts[1]
self.tp_event = parts[2]
self.library = "" # kernel
self.function = "" # from TRACEPOINT_PROBE
elif self.probe_type == "u":
# u:<library>[:<provider>]:<probe> where :<provider> is optional
self.library = parts[1]
self.usdt_name = ":".join(parts[2:])
self.function = "" # no function, just address
# We will discover the USDT provider by matching on
# the USDT name in the specified library
self._find_usdt_probe()
else:
self.library = ':'.join(parts[1:-1])
self.function = parts[-1]
# only x64 syscalls needs checking, no other syscall wrapper yet.
self.is_syscall_kprobe = False
if self.probe_type == "p" and len(self.library) == 0 and \
self.function[:10] == "__x64_sys_":
self.is_syscall_kprobe = True
def _find_usdt_probe(self):
target = Probe.pid if Probe.pid and Probe.pid != -1 \
else Probe.tgid
self.usdt = USDT(path=self.library, pid=target)
parts = self.usdt_name.split(":")
if len(parts) == 1:
provider_name = None
usdt_name = parts[0].encode("ascii")
else:
provider_name = parts[0].encode("ascii")
usdt_name = parts[1].encode("ascii")
for probe in self.usdt.enumerate_probes():
if ((not provider_name or probe.provider == provider_name)
and probe.name == usdt_name):
return # Found it, will enable later
self._bail("unrecognized USDT probe %s" % self.usdt_name)
def _parse_filter(self, filt):
self.filter = self._rewrite_expr(filt)
def _parse_types(self, fmt):
for match in re.finditer(
r'[^%]%(s|u|d|lu|llu|ld|lld|hu|hd|x|lx|llx|c|K|U)', fmt):
self.types.append(match.group(1))
fmt = re.sub(r'([^%]%)(u|d|lu|llu|ld|lld|hu|hd)', r'\1d', fmt)
fmt = re.sub(r'([^%]%)(x|lx|llx)', r'\1x', fmt)
fmt = re.sub('%K|%U', '%s', fmt)
self.python_format = fmt.strip('"')
def _parse_action(self, action):
self.values = []
self.types = []
self.python_format = ""
if len(action) == 0:
return
action = action.strip()
match = re.search(r'(\".*?\"),?(.*)', action)
if match is None:
self._bail("expected format string in \"s")
self.raw_format = match.group(1)
self._parse_types(self.raw_format)
for part in re.split('(?<!"),', match.group(2)):
part = self._rewrite_expr(part)
if len(part) > 0:
self.values.append(part)
aliases_arg = {
"arg1": "PT_REGS_PARM1(ctx)",
"arg2": "PT_REGS_PARM2(ctx)",
"arg3": "PT_REGS_PARM3(ctx)",
"arg4": "PT_REGS_PARM4(ctx)",
"arg5": "PT_REGS_PARM5(ctx)",
"arg6": "PT_REGS_PARM6(ctx)",
}
aliases_indarg = {
"arg1": "({u64 _val; struct pt_regs *_ctx = (struct pt_regs *)PT_REGS_PARM1(ctx);"
" bpf_probe_read_kernel(&_val, sizeof(_val), &(PT_REGS_PARM1(_ctx))); _val;})",
"arg2": "({u64 _val; struct pt_regs *_ctx = (struct pt_regs *)PT_REGS_PARM1(ctx);"
" bpf_probe_read_kernel(&_val, sizeof(_val), &(PT_REGS_PARM2(_ctx))); _val;})",
"arg3": "({u64 _val; struct pt_regs *_ctx = (struct pt_regs *)PT_REGS_PARM1(ctx);"
" bpf_probe_read_kernel(&_val, sizeof(_val), &(PT_REGS_PARM3(_ctx))); _val;})",
"arg4": "({u64 _val; struct pt_regs *_ctx = (struct pt_regs *)PT_REGS_PARM1(ctx);"
" bpf_probe_read_kernel(&_val, sizeof(_val), &(PT_REGS_PARM4(_ctx))); _val;})",
"arg5": "({u64 _val; struct pt_regs *_ctx = (struct pt_regs *)PT_REGS_PARM1(ctx);"
" bpf_probe_read_kernel(&_val, sizeof(_val), &(PT_REGS_PARM5(_ctx))); _val;})",
"arg6": "({u64 _val; struct pt_regs *_ctx = (struct pt_regs *)PT_REGS_PARM1(ctx);"
" bpf_probe_read_kernel(&_val, sizeof(_val), &(PT_REGS_PARM6(_ctx))); _val;})",
}
aliases_common = {
"retval": "PT_REGS_RC(ctx)",
"$uid": "(unsigned)(bpf_get_current_uid_gid() & 0xffffffff)",
"$gid": "(unsigned)(bpf_get_current_uid_gid() >> 32)",
"$pid": "(unsigned)(bpf_get_current_pid_tgid() & 0xffffffff)",
"$tgid": "(unsigned)(bpf_get_current_pid_tgid() >> 32)",
"$cpu": "bpf_get_smp_processor_id()",
"$task": "((struct task_struct *)bpf_get_current_task())"
}
def _rewrite_expr(self, expr):
# Find the occurances of any arg[1-6]@user. Use it later to
# identify bpf_probe_read_user
for matches in re.finditer(r'(arg[1-6])(@user)', expr):
if matches.group(1).strip() not in self.probe_user_list:
self.probe_user_list.add(matches.group(1).strip())
# Remove @user occurrences from arg before resolving to its
# corresponding aliases.
expr = re.sub(r'(arg[1-6])@user', r'\1', expr)
rdict = StrcmpRewrite.rewrite_expr(expr,
self.bin_cmp, self.library,
self.probe_user_list, self.streq_functions,
Probe.streq_index)
expr = rdict["expr"]
self.streq_functions = rdict["streq_functions"]
Probe.streq_index = rdict["probeid"]
alias_to_check = Probe.aliases_indarg \
if self.is_syscall_kprobe \
else Probe.aliases_arg
# For USDT probes, we replace argN values with the
# actual arguments for that probe obtained using
# bpf_readarg_N macros emitted at BPF construction.
if not self.probe_type == "u":
for alias, replacement in alias_to_check.items():
expr = expr.replace(alias, replacement)
for alias, replacement in Probe.aliases_common.items():
expr = expr.replace(alias, replacement)
return expr
c_type = {"u": "unsigned int", "d": "int",
"lu": "unsigned long", "ld": "long",
"llu": "unsigned long long", "lld": "long long",
"hu": "unsigned short", "hd": "short",
"x": "unsigned int", "lx": "unsigned long",
"llx": "unsigned long long",
"c": "char", "K": "unsigned long long",
"U": "unsigned long long"}
fmt_types = c_type.keys()
def _generate_field_decl(self, idx):
field_type = self.types[idx]
if field_type == "s":
return "char v%d[%d];\n" % (idx, self.string_size)
if field_type in Probe.fmt_types:
return "%s v%d;\n" % (Probe.c_type[field_type], idx)
self._bail("unrecognized format specifier %s" % field_type)
def _generate_data_decl(self):
# The BPF program will populate values into the struct
# according to the format string, and the Python program will
# construct the final display string.
self.events_name = "%s_events" % self.probe_name
self.struct_name = "%s_data_t" % self.probe_name
self.stacks_name = "%s_stacks" % self.probe_name
stack_type = "BPF_STACK_TRACE" if self.build_id_enabled is False \
else "BPF_STACK_TRACE_BUILDID"
stack_table = "%s(%s, 1024);" % (stack_type, self.stacks_name) \
if (self.kernel_stack or self.user_stack) else ""
data_fields = ""
for i, field_type in enumerate(self.types):
data_fields += " " + \
self._generate_field_decl(i)
time_str = "u64 timestamp_ns;" if self.time_field else ""
cpu_str = "int cpu;" if self.print_cpu else ""
kernel_stack_str = " int kernel_stack_id;" \
if self.kernel_stack else ""
user_stack_str = " int user_stack_id;" \
if self.user_stack else ""
text = """
struct %s
{
%s
%s
u32 tgid;
u32 pid;
char comm[TASK_COMM_LEN];
%s
%s
%s
u32 uid;
};
BPF_PERF_OUTPUT(%s);
%s
"""
return text % (self.struct_name, time_str, cpu_str, data_fields,
kernel_stack_str, user_stack_str,
self.events_name, stack_table)
def _generate_field_assign(self, idx):
field_type = self.types[idx]
expr = self.values[idx].strip()
text = ""
if self.probe_type == "u" and expr[0:3] == "arg":
arg_index = int(expr[3])
arg_ctype = self.usdt.get_probe_arg_ctype(
self.usdt_name, arg_index - 1)
text = (" %s %s = 0;\n" +
" bpf_usdt_readarg(%s, ctx, &%s);\n") \
% (arg_ctype, expr, expr[3], expr)
probe_read_func = "bpf_probe_read_kernel"
if field_type == "s":
if self.library:
probe_read_func = "bpf_probe_read_user"
else:
alias_to_check = Probe.aliases_indarg \
if self.is_syscall_kprobe \
else Probe.aliases_arg
for arg, alias in alias_to_check.items():
if alias == expr and arg in self.probe_user_list:
probe_read_func = "bpf_probe_read_user"
break
return text + """
if (%s != 0) {
void *__tmp = (void *)%s;
%s(&__data.v%d, sizeof(__data.v%d), __tmp);
}
""" % (expr, expr, probe_read_func, idx, idx)
if field_type in Probe.fmt_types:
return text + " __data.v%d = (%s)%s;\n" % \
(idx, Probe.c_type[field_type], expr)
self._bail("unrecognized field type %s" % field_type)
def _generate_usdt_filter_read(self):
text = ""
if self.probe_type != "u":
return text
for arg, _ in Probe.aliases_arg.items():
if not (arg in self.filter):
continue
arg_index = int(arg.replace("arg", ""))
arg_ctype = self.usdt.get_probe_arg_ctype(
self.usdt_name, arg_index - 1)
if not arg_ctype:
self._bail("Unable to determine type of {} "
"in the filter".format(arg))
text += """
{} {}_filter;
bpf_usdt_readarg({}, ctx, &{}_filter);
""".format(arg_ctype, arg, arg_index, arg)
self.filter = self.filter.replace(
arg, "{}_filter".format(arg))
return text
def generate_program(self, include_self):
data_decl = self._generate_data_decl()
if Probe.pid != -1:
pid_filter = """
if (__pid != %d) { return 0; }
""" % Probe.pid
# uprobes can have a built-in tgid filter passed to
# attach_uprobe, hence the check here -- for kprobes, we
# need to do the tgid test by hand:
elif len(self.library) == 0 and Probe.tgid != -1:
pid_filter = """
if (__tgid != %d) { return 0; }
""" % Probe.tgid
elif not include_self:
pid_filter = """
if (__tgid == %d) { return 0; }
""" % os.getpid()
else:
pid_filter = ""
if Probe.uid != -1:
uid_filter = """
if (__uid != %d) { return 0; }
""" % Probe.uid
else:
uid_filter = ""
if self.cgroup_map_name is not None:
cgroup_filter = """
if (%s.check_current_task(0) <= 0) { return 0; }
""" % self.cgroup_map_name
else:
cgroup_filter = ""
prefix = ""
signature = "struct pt_regs *ctx"
if self.signature:
signature += ", " + self.signature
data_fields = ""
for i, expr in enumerate(self.values):
data_fields += self._generate_field_assign(i)
if self.probe_type == "t":
heading = "TRACEPOINT_PROBE(%s, %s)" % \
(self.tp_category, self.tp_event)
ctx_name = "args"
else:
heading = "int %s(%s)" % (self.probe_name, signature)
ctx_name = "ctx"
time_str = """
__data.timestamp_ns = bpf_ktime_get_ns();""" if self.time_field else ""
cpu_str = """
__data.cpu = bpf_get_smp_processor_id();""" if self.print_cpu else ""
stack_trace = ""
if self.user_stack:
stack_trace += """
__data.user_stack_id = %s.get_stackid(
%s, BPF_F_USER_STACK
);""" % (self.stacks_name, ctx_name)
if self.kernel_stack:
stack_trace += """
__data.kernel_stack_id = %s.get_stackid(
%s, 0
);""" % (self.stacks_name, ctx_name)
text = heading + """
{
u64 __pid_tgid = bpf_get_current_pid_tgid();
u32 __tgid = __pid_tgid >> 32;
u32 __pid = __pid_tgid; // implicit cast to u32 for bottom half
u32 __uid = bpf_get_current_uid_gid();
%s
%s
%s
%s
%s
if (!(%s)) return 0;
struct %s __data = {0};
%s
%s
__data.tgid = __tgid;
__data.pid = __pid;
__data.uid = __uid;
bpf_get_current_comm(&__data.comm, sizeof(__data.comm));
%s
%s
%s.perf_submit(%s, &__data, sizeof(__data));
return 0;
}
"""
text = text % (pid_filter, uid_filter, cgroup_filter, prefix,
self._generate_usdt_filter_read(), self.filter,
self.struct_name, time_str, cpu_str, data_fields,
stack_trace, self.events_name, ctx_name)
return self.streq_functions + data_decl + "\n" + text
@classmethod
def _time_off_str(cls, timestamp_ns):
offset = 1e-9 * (timestamp_ns - cls.first_ts)
if cls.print_unix_timestamp:
return "%.6f" % (offset + cls.first_ts_real)
else:
return "%.6f" % offset
def _display_function(self):
if self.probe_type == 'p' or self.probe_type == 'r':
return self.function
elif self.probe_type == 'u':
return self.usdt_name
else: # self.probe_type == 't'
return self.tp_event
def _stack_to_string(self, bpf, stack_id, tgid):
if stack_id < 0:
return (" %d" % stack_id)
stackstr = ''
stack = list(bpf.get_table(self.stacks_name).walk(stack_id))
for addr in stack:
stackstr += ' '
if Probe.print_address:
stackstr += ("%16x " % addr)
symstr = bpf.sym(addr, tgid, show_module=True, show_offset=True)
stackstr += ('%s\n' % (symstr.decode('utf-8')))
return stackstr
def _format_message(self, bpf, tgid, values):
# Replace each %K with kernel sym and %U with user sym in tgid
kernel_placeholders = [i for i, t in enumerate(self.types)
if t == 'K']
user_placeholders = [i for i, t in enumerate(self.types)
if t == 'U']
string_placeholders = [i for i, t in enumerate(self.types)
if t == 's']
for kp in kernel_placeholders:
values[kp] = bpf.ksym(values[kp], show_offset=True)
for up in user_placeholders:
values[up] = bpf.sym(values[up], tgid,
show_module=True, show_offset=True)
for sp in string_placeholders:
values[sp] = values[sp].decode('utf-8', 'replace')
return self.python_format % tuple(values)
def print_aggregate_events(self):
for k, v in sorted(self.symcount.items(), key=lambda item: \
item[1], reverse=True):
print("%s-->COUNT %d\n\n" % (k, v), end="")
def print_event(self, bpf, cpu, data, size):
event = bpf[self.events_name].event(data)
if self.name not in event.comm:
return
values = list(map(lambda i: getattr(event, "v%d" % i),
range(0, len(self.values))))
msg = self._format_message(bpf, event.tgid, values)
if self.msg_filter and self.msg_filter not in msg:
return
eventstr = ''
if Probe.print_time:
time = strftime("%H:%M:%S") if Probe.use_localtime else \
Probe._time_off_str(event.timestamp_ns)
if Probe.print_unix_timestamp:
eventstr += ("%-17s " % time[:17])
else:
eventstr += ("%-8s " % time[:8])
if Probe.print_cpu:
eventstr += ("%-3s " % event.cpu)
eventstr += ("%-7d %-7d %-15s %-16s %s\n" %
(event.tgid, event.pid,
event.comm.decode('utf-8', 'replace'),
self._display_function(), msg))
if self.kernel_stack:
eventstr += self._stack_to_string(bpf, event.kernel_stack_id, -1)
if self.user_stack:
eventstr += self._stack_to_string(bpf, event.user_stack_id, event.tgid)
if self.aggregate is False:
print(eventstr, end="")
if self.kernel_stack or self.user_stack:
print("")
else:
if eventstr in self.symcount:
self.symcount[eventstr] += 1
else:
self.symcount[eventstr] = 1
Probe.event_count += 1
if Probe.max_events is not None and \
Probe.event_count >= Probe.max_events:
if self.aggregate:
self.print_aggregate_events()
sys.stdout.flush()
Probe.done = True;
def attach(self, bpf, verbose):
if len(self.library) == 0:
self._attach_k(bpf)
else:
self._attach_u(bpf)
callback = partial(self.print_event, bpf)
bpf[self.events_name].open_perf_buffer(callback,
page_cnt=self.page_cnt)
def _attach_k(self, bpf):
if self.probe_type == "r":
bpf.attach_kretprobe(event=self.function,
fn_name=self.probe_name)
elif self.probe_type == "p":
bpf.attach_kprobe(event=self.function,
fn_name=self.probe_name,
event_off=self.offset)
# Note that tracepoints don't need an explicit attach
def _attach_u(self, bpf):
libpath = BPF.find_library(self.library)
if libpath is None:
# This might be an executable (e.g. 'bash')
libpath = BPF.find_exe(self.library)
if libpath is None or len(libpath) == 0:
self._bail("unable to find library %s" % self.library)
if self.probe_type == "u":
pass # Was already enabled by the BPF constructor
elif self.probe_type == "r":
bpf.attach_uretprobe(name=libpath,
sym=self.function,
fn_name=self.probe_name,
pid=Probe.tgid)
else:
bpf.attach_uprobe(name=libpath,
sym=self.function,
fn_name=self.probe_name,
pid=Probe.tgid,
sym_off=self.offset)
class Tool(object):
DEFAULT_PERF_BUFFER_PAGES = 64
examples = """
EXAMPLES:
trace do_sys_open
Trace the open syscall and print a default trace message when entered
trace kfree_skb+0x12
Trace the kfree_skb kernel function after the instruction on the 0x12 offset
trace 'do_sys_open "%s", arg2@user'
Trace the open syscall and print the filename being opened @user is
added to arg2 in kprobes to ensure that char * should be copied from
the userspace stack to the bpf stack. If not specified, previous
behaviour is expected.
trace 'do_sys_open "%s", arg2@user' -n main
Trace the open syscall and only print event that process names containing "main"
trace 'do_sys_open "%s", arg2@user' --uid 1001
Trace the open syscall and only print event that processes with user ID 1001
trace 'do_sys_open "%s", arg2@user' -f config
Trace the open syscall and print the filename being opened filtered by "config"
trace 'sys_read (arg3 > 20000) "read %d bytes", arg3'
Trace the read syscall and print a message for reads >20000 bytes
trace 'r::do_sys_open "%llx", retval'
Trace the return from the open syscall and print the return value
trace 'c:open (arg2 == 42) "%s %d", arg1, arg2'
Trace the open() call from libc only if the flags (arg2) argument is 42
trace 'c:malloc "size = %d", arg1'
Trace malloc calls and print the size being allocated
trace 'p:c:write (arg1 == 1) "writing %d bytes to STDOUT", arg3'
Trace the write() call from libc to monitor writes to STDOUT
trace 'r::__kmalloc (retval == 0) "kmalloc failed!"'
Trace returns from __kmalloc which returned a null pointer
trace 'r:c:malloc (retval) "allocated = %x", retval'
Trace returns from malloc and print non-NULL allocated buffers
trace 't:block:block_rq_complete "sectors=%d", args->nr_sector'
Trace the block_rq_complete kernel tracepoint and print # of tx sectors
trace 'u:pthread:pthread_create (arg4 != 0)'
Trace the USDT probe pthread_create when its 4th argument is non-zero
trace 'u:pthread:libpthread:pthread_create (arg4 != 0)'
Ditto, but the provider name "libpthread" is specified.
trace 'p::SyS_nanosleep(struct timespec *ts) "sleep for %lld ns", ts->tv_nsec'
Trace the nanosleep syscall and print the sleep duration in ns
trace -c /sys/fs/cgroup/system.slice/workload.service '__x64_sys_nanosleep' '__x64_sys_clone'
Trace nanosleep/clone syscall calls only under workload.service
cgroup hierarchy.
trace -I 'linux/fs.h' \\
'p::uprobe_register(struct inode *inode) "a_ops = %llx", inode->i_mapping->a_ops'
Trace the uprobe_register inode mapping ops, and the symbol can be found
in /proc/kallsyms
trace -I 'kernel/sched/sched.h' \\
'p::__account_cfs_rq_runtime(struct cfs_rq *cfs_rq) "%d", cfs_rq->runtime_remaining'
Trace the cfs scheduling runqueue remaining runtime. The struct cfs_rq is defined
in kernel/sched/sched.h which is in kernel source tree and not in kernel-devel
package. So this command needs to run at the kernel source tree root directory
so that the added header file can be found by the compiler.
trace -I 'net/sock.h' \\
'udpv6_sendmsg(struct sock *sk) (sk->sk_dport == 13568)'
Trace udpv6 sendmsg calls only if socket's destination port is equal
to 53 (DNS; 13568 in big endian order)
trace -I 'linux/fs_struct.h' 'mntns_install "users = %d", $task->fs->users'
Trace the number of users accessing the file system of the current task
trace -s /lib/x86_64-linux-gnu/libc.so.6,/bin/ping 'p:c:inet_pton' -U
Trace inet_pton system call and use the specified libraries/executables for
symbol resolution.
"""
def __init__(self):
parser = argparse.ArgumentParser(description="Attach to " +
"functions and print trace messages.",
formatter_class=argparse.RawDescriptionHelpFormatter,
epilog=Tool.examples)
parser.add_argument("-b", "--buffer-pages", type=int,
default=Tool.DEFAULT_PERF_BUFFER_PAGES,
help="number of pages to use for perf_events ring buffer "
"(default: %(default)d)")
# we'll refer to the userspace concepts of "pid" and "tid" by
# their kernel names -- tgid and pid -- inside the script
parser.add_argument("-p", "--pid", type=int, metavar="PID",
dest="tgid", help="id of the process to trace (optional)")
parser.add_argument("-L", "--tid", type=int, metavar="TID",
dest="pid", help="id of the thread to trace (optional)")
parser.add_argument("--uid", type=int, metavar="UID",
dest="uid", help="id of the user to trace (optional)")
parser.add_argument("-v", "--verbose", action="store_true",
help="print resulting BPF program code before executing")
parser.add_argument("-Z", "--string-size", type=int,
default=80, help="maximum size to read from strings")
parser.add_argument("-S", "--include-self",
action="store_true",
help="do not filter trace's own pid from the trace")
parser.add_argument("-M", "--max-events", type=int,
help="number of events to print before quitting")
parser.add_argument("-t", "--timestamp", action="store_true",
help="print timestamp column (offset from trace start)")
parser.add_argument("-u", "--unix-timestamp", action="store_true",
help="print UNIX timestamp instead of offset from trace start, requires -t")
parser.add_argument("-T", "--time", action="store_true",
help="print time column")
parser.add_argument("-C", "--print_cpu", action="store_true",
help="print CPU id")
parser.add_argument("-c", "--cgroup-path", type=str,
metavar="CGROUP_PATH", dest="cgroup_path",
help="cgroup path")
parser.add_argument("-n", "--name", type=str,
help="only print process names containing this name")
parser.add_argument("-f", "--msg-filter", type=str, dest="msg_filter",
help="only print the msg of event containing this string")
parser.add_argument("-B", "--bin_cmp", action="store_true",
help="allow to use STRCMP with binary values")
parser.add_argument('-s', "--sym_file_list", type=str,
metavar="SYM_FILE_LIST", dest="sym_file_list",
help="comma separated list of symbol files to use \
for symbol resolution")
parser.add_argument("-K", "--kernel-stack",
action="store_true", help="output kernel stack trace")
parser.add_argument("-U", "--user-stack",
action="store_true", help="output user stack trace")
parser.add_argument("-a", "--address", action="store_true",
help="print virtual address in stacks")
parser.add_argument(metavar="probe", dest="probes", nargs="+",
help="probe specifier (see examples)")
parser.add_argument("-I", "--include", action="append",
metavar="header",
help="additional header files to include in the BPF program "
"as either full path, "
"or relative to current working directory, "
"or relative to default kernel header search path")
parser.add_argument("-A", "--aggregate", action="store_true",
help="aggregate amount of each trace")
parser.add_argument("--ebpf", action="store_true",
help=argparse.SUPPRESS)
self.args = parser.parse_args()
if self.args.tgid and self.args.pid:
parser.error("only one of -p and -L may be specified")
if self.args.cgroup_path is not None:
self.cgroup_map_name = "__cgroup"
else:
self.cgroup_map_name = None
def _create_probes(self):
Probe.configure(self.args)
self.probes = []
for probe_spec in self.args.probes:
self.probes.append(Probe(
probe_spec, self.args.string_size,
self.args.kernel_stack, self.args.user_stack,
self.cgroup_map_name, self.args.name, self.args.msg_filter))
def _generate_program(self):
self.program = """
#include <linux/ptrace.h>
#include <linux/sched.h> /* For TASK_COMM_LEN */
"""
for include in (self.args.include or []):
if include.startswith((".", "/")):
include = os.path.abspath(include)
self.program += "#include \"%s\"\n" % include
else:
self.program += "#include <%s>\n" % include
self.program += BPF.generate_auto_includes(
map(lambda p: p.raw_probe, self.probes))
if self.cgroup_map_name is not None:
self.program += "BPF_CGROUP_ARRAY(%s, 1);\n" % \
self.cgroup_map_name
for probe in self.probes:
self.program += probe.generate_program(
self.args.include_self)
if self.args.verbose or self.args.ebpf:
print(self.program)
if self.args.ebpf:
exit()
def _attach_probes(self):
usdt_contexts = []
for probe in self.probes:
if probe.usdt:
# USDT probes must be enabled before the BPF object
# is initialized, because that's where the actual
# uprobe is being attached.
probe.usdt.enable_probe(
probe.usdt_name, probe.probe_name)
if self.args.verbose:
print(probe.usdt.get_text())
usdt_contexts.append(probe.usdt)
self.bpf = BPF(text=self.program, usdt_contexts=usdt_contexts)
if self.args.sym_file_list is not None:
print("Note: Kernel bpf will report stack map with ip/build_id")
map(lambda x: self.bpf.add_module(x), self.args.sym_file_list.split(','))
# if cgroup filter is requested, update the cgroup array map
if self.cgroup_map_name is not None:
cgroup_array = self.bpf.get_table(self.cgroup_map_name)
cgroup_array[0] = self.args.cgroup_path
for probe in self.probes:
if self.args.verbose:
print(probe)
probe.attach(self.bpf, self.args.verbose)
def _main_loop(self):
all_probes_trivial = all(map(Probe.is_default_action,
self.probes))
# Print header
if self.args.timestamp or self.args.time:
col_fmt = "%-17s " if self.args.unix_timestamp else "%-8s "
print(col_fmt % "TIME", end="")
if self.args.print_cpu:
print("%-3s " % "CPU", end="")
print("%-7s %-7s %-15s %-16s %s" %
("PID", "TID", "COMM", "FUNC",
"-" if not all_probes_trivial else ""))
sys.stdout.flush()
while not Probe.done:
self.bpf.perf_buffer_poll()
def run(self):
try:
self._create_probes()
self._generate_program()
self._attach_probes()
self._main_loop()
except:
exc_info = sys.exc_info()
sys_exit = exc_info[0] is SystemExit
if self.args.verbose:
traceback.print_exc()
elif not sys_exit:
print(exc_info[1])
exit(0 if sys_exit else 1)
if __name__ == "__main__":
Tool().run()
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